1. Field of the Invention
The present disclosure relates generally to input/output processing, and in particular, to communications between an operating system and input/output system devices.
2. Description of Background
Input/output (I/O) operations are used to transfer data between memory and I/O devices of an I/O processing system. Specifically, data is written from memory to one or more I/O devices, and data is read from one or more I/O devices to memory by executing I/O operations.
To facilitate processing of I/O operations, an I/O subsystem of the I/O processing system is employed. The I/O subsystem is coupled to main memory and the I/O devices of the I/O processing system and directs the flow of information between memory and the I/O devices. One example of an I/O subsystem is a channel subsystem. The channel subsystem uses channel paths as communications media. Each channel path includes a channel coupled to a control unit, the control unit being further coupled to one or more I/O devices.
Fibre Channel interfaces architecture, as standardized in the T11 Technical Committee of the International Committee for Information Technology Standards (INCITS) is the standard for defining connections in many networks, such as storage area networks (SANs). These standards include several sets of services which have historically been used by a computer system's I/O subsystem to determine and configure the various devices and links within a SAN. Fibre-channel services may also be used to further configure SAN devices and links to be allocated and/or shared among the multiple logical partitions that may be defined in an enterprise class server. Many fiber-channel systems do not define an interface that allows software to directly request information, specifically network topological information, from devices or other endpoints in the I/O subsystem.